Absence of time reversal symmetry breaking in La_{2-x}Sr_{x}CuO_{4}

TL;DR

This study used muon spin rotation to investigate whether La_{2-x}Sr_{x}CuO_{4} exhibits spontaneous magnetic fields indicative of time-reversal symmetry breaking in the pseudo-gap state, finding no evidence for such phenomena.

Contribution

The paper provides the first strict upper limits on time-reversal symmetry breaking fields in La_{2-x}Sr_{x}CuO_{4}, challenging circulating current theories of the pseudo-gap.

Findings

No detectable spontaneous magnetic fields in the pseudo-gap state.

Circulating current states are effectively ruled out in this material.

Results constrain theoretical models of the pseudo-gap phase.

Abstract

We have performed zero-field muon spin rotation measurements on single crystals of La_{2-x}Sr_{x}CuO_{4} to search for spontaneous currents in the pseudo-gap state. By comparing measurements on materials across the phase diagram, we put strict upper limits on any possible time-reversal symmetry breaking fields that could be associated with the pseudo-gap. Comparison between experimental limits and proposed circulating current states effectively eliminates the possibility that such states exist in this family of materials.